furnace not working

[Sam]

As you can see, I have a 2014 Seneca TS. A few weeks ago while in CA my furnace started acting up. At first the burner would not ignite at times after the blower would come on. The blower would run for about ten seconds then shut down. Then the burner stopped igniting altogether. I reset the rocker switch in the outside panel and it worked for a time then stopped working. I should add the blower would go on for approx. 10/15 seconds and then stop after the burner failed to ignite. I had a tech. work on it and it again worked for a short time and then stopped. The tech really did nothing except reset the outside rocker switch. I also should add I was on shore power, 50 amp and all other electrics work, and yes, full tank of propane. We are home now in rural CO and the closet RV repair is 60 miles. I can do my on repairs if I know what to do.

My online research as well as careful reading of the manual indicates it may be the DSI igniter board, (Ignition-adapter universal DSI board).

Atwood furnace Model 8940-III DCLP. Any suggestion would be appreciated. Thanks, Sam

[wags999]

Originally Posted by Sam

As you can see, I have a 2014 Seneca TS. A few weeks ago while in CA my furnace started acting up. At first the burner would not ignite at times after the blower would come on. The blower would run for about ten seconds then shut down. Then the burner stopped igniting altogether. I reset the rocker switch in the outside panel and it worked for a time then stopped working. I should add the blower would go on for approx. 10/15 seconds and then stop after the burner failed to ignite. I had a tech. work on it and it again worked for a short time and then stopped. The tech really did nothing except reset the outside rocker switch. I also should add I was on shore power, 50 amp and all other electrics work, and yes, full tank of propane. We are home now in rural CO and the closet RV repair is 60 miles. I can do my on repairs if I know what to do.

My online research as well as careful reading of the manual indicates it may be the DSI igniter board, (Ignition-adapter universal DSI board).

Atwood furnace Model 8940-III DCLP. Any suggestion would be appreciated. Thanks, Sam

This sounds like an issue I had, which did turn out to be a board issue. These boards can be damaged with just static electric. The blower comes on, it triggers an sail switch, which makes sure you have good air movement, and that will turn on the gas, allowing the igniter to do it's job. It could be a stuck sail switch which you can check if you remove the heater unit. When you reset the unit, you need to turn the reset switch off, and leave it off for a minute or two before resetting it.

Good Luck.

[BullDozerBob]

Trail for ignition only last the 10 seconds so if it lights then goes out I would suspect a dirty flame sensor which is the same component where the arc occurs.
Use the sandpaper from a match book or the blade of a small knife to scrape the sensor to clean it. The gap to ground[burner] is 1/8 inch.
Check these first b/4 replacing the board. Fenwall boards are common and always want to to a high flame signal.
Five campers, two motor homes and 40 years as an HVAC Tech.
Hope this helps.

BullDozerBob

[Oklahoma Dan]

Furnace failure due to water getting in through panel on outside and shorting out circuit board located where it can get soaked by rain or just washing your coach. Dealer stated that many problems of this nature commonly happening due to a redesign on some units over the last couple of years. There is a thread I have found on the Thor Forum that goes into what happened to my furnace. Worth looking at if this is your problem. Hope this helps you.

Rain getting in disables furnace on 2016 ACE 2016 - Thor Forums

[kurv]

I had mine quit working yesterday. I washed the motorhome two days prior, the next day everything froze. The blower would turn on run for 10 seconds and shut down without ever igniting. The diagnostic led blinked a code for "airflow or limit switch problem". I kind of suspected it was a froze switch so I took off the inside cover to access the duct work inside furnace. I took my wifes hairdryer and blew hot air through the unit, then blew it through the vent outside. Furnace fired up after that.

[Oklahoma Dan]

Yea I have a 2015 Greyhawk 31-FS. Dealer replaced 14 circuit boards on other motorhomes with Atwood furnaces before mine due to the same problem. Instead of outward, those exterior grates go inward allowing water to easily penetrate circuit board that mfg. began installing on the bottom/floor of the furnace compartment. New circuit board solved problem along with relocating it off of the bottom/floor so it won't get wet. Atwood or Jayco (not sure which) provided dealer the board and labor calling it a latent defect covering the costs. The link I posted pretty much explains what Thor owners found. Have not seen this problem widely discussed on this Forum but it seems to be rather widespread regardless.

[BullDozerBob]

That and some quality control and communication to the dealers.
No excuse for the frustration it causes the RV owner.

[Sam]

For information, I was able to fix my furnace problem. After reading much info, I replaced the sail switch. This fixed the the problem and it works. The best part is a replacement sail switch is less than $20.
Sam

[PrairieWanderer]

Sam, I have the same furnace problem you describe above in my 2015 37TS. Was it much of a job to get at the sail switch to check or replace it. Mine started acting up last fall just before we left Alaska and its been in storage since getting home. Got to get it working again before our next trip. Thanks Mark

[Sam]

PrairieWanderer. To replace the sail switch is easy. The switch is located in the outside compartment that contains the heater. Of course remove the cover and you will observe the DSI ignition board on the left fastened to the side wall. In about the center of the compartment you will see a square metal cover that covers the round cage type blower. (The cover is about 4"X4".) Remove the four screws and the cover comes off easily. The sail switch will be located close to the blower. The sail switch insures that there is enough volume of air passing through the vent before the burner will ignite. If it is not the sail switch it could be the DSI igniter board. Most of what I learned is it most likely the sail switch.

When you turn on the furnace, the blower should come on and run for five to ten seconds then you should hear the burner ignite.

I was able to obtain a sail switch locally for $18. A new DSI igniter board could cost near $200.

Believe me, I am not a furnace expert, however, I got luckey.
Hope this helps, Sam

[nunyadamn]

Originally Posted by Sam

For information, I was able to fix my furnace problem. After reading much info, I replaced the sail switch. This fixed the the problem and it works. The best part is a replacement sail switch is less than $20.
Sam

I was just about to say the same thing. I had one fail on my old Class C.

[PrairieWanderer]

Sam, thanks for your reply. Suppose to warm up here into mid forties on Friday and I plan on getting into it. Mark